1. Field of the Invention
The present invention relates to a maintenance liquid for use in an ink jet recording apparatus.
2. Background Art
Ink jet printers have been commercialized as noiseless, high-speed, and high-resolution non-impact printers. Inks used in ink jet recording are mainly water-base inks using water and water-soluble organic solvents from the viewpoints of odor, safety and the like. Water-soluble dyes have hitherto been utilized as colorants for inks for use in ink jet recording. In recent years, from the viewpoint of improving print quality, there is a tendency toward an increase in the content of dye in the ink. Further, the use of pigments instead of water-soluble dyes is recently being expanded from the viewpoint of improving print quality and fastness properties of images.
In ink jet recording, ink is ejected through nozzles having a very small diameter of about 20 to 50 μm. Therefore, thickening and precipitation in the ink are likely to occur in a portion around the front end of nozzles due to evaporation of a low-boiling solvent, colorant separation and coagulation and the like. These unfavorable phenomena sometimes lead to troubles such as print disorder and nozzle clogging. They are likely to take place after a halt of the apparatus for a long period of time.
Methods which have been proposed for preventing these problems include (1) a method in which, upon the occurrence of troubles, the ink passage is cleaned with a cleaning liquid, and (2) a method in which, when a halt of the apparatus for a long period of time is expected, the ink is previously replaced by a maintenance liquid. In both the above methods, the attained effect depends greatly upon cleaning properties of the cleaning liquid or the maintenance liquid used.
Examples of cleaning liquids or maintenance liquids include a maintenance liquid comprising a polyhydric alcohol, a monohydric alcohol, and water (for example, Japanese Patent Publication No. 8437/1994), a maintenance liquid comprising a monohydric alcohol, an anionic surfactant, and water (for example, Japanese Patent Publication No. 30200/1996), an isothiazolone compound-containing cleaning liquid having improved antimold/antimicrobial effect (for example, Japanese Patent Laid-Open No. 261476/1992), a silicone antifoaming agent-containing cleaning liquid having improved antifoaming properties (for example, Japanese Patent Laid-Open No. 328093/2000), and a maintenance liquid having pH 8 to 11 applicable in the case where a particular crosslinkable ink is used (for example, Japanese Patent Laid-Open No. 109733/2000).
However, there is still a need for a maintenance liquid having better cleaning properties. In particular, it can be said that the above-described recent tendency toward an increase in colorant content of ink and expansion of use of pigments has led to a demand for a maintenance liquid having better cleaning properties.